Hi All,

I'm Perl newbie and I'm facing problem with $title. My script reads the pcap file using Net::Pcap and NetPacket. Script reads packet by packet, stripping them out of headers (Ethernet/IP/TCP) and takes only payload part. Then I don't know how to convert payload into readable text.

My code:

use Net::Pcap;
use NetPacket::Ethernet;
use NetPacket::IP;
use NetPacket::TCP;
use NetPacket::UDP;
use NetPacket::ICMP;
use strict;

sub parsePayload
{
   my($payload, $text) = @_;
   # now i don't know what to do
   my $data = pack("A",$payload);
   print "Data: $data\n";
}

sub getPayload
{
   my ($userdata, $header, $packet) = @_;

   my $ether_data = NetPacket::Ethernet::strip($packet);

   my $ip = NetPacket::IP->decode($ether_data);
   if ( $ip->{'proto'} == 6 )
   {
      print "TCP\n";
      my $l4 = NetPacket::IP::strip($ether_data);
      my $tcp = NetPacket::TCP->decode($l4);
      my $payload = $tcp->{'data'};
      &parsePayload("$payload","$userdata");
   }
   elsif ( $ip->{'proto'} == 17)
   {
      print "UDP\n";
      my $l4 = NetPacket::IP::strip($ether_data);
      my $udp = NetPacket::UDP->decode($l4);
      my $payload = $udp->{'data'};
      
      &parsePayload("$payload","$userdata");
   }
   elsif ( $ip->{'proto'} == 1)
   {
      print "ICMP";
      my $l4 = NetPacket::IP::strip($ether_data);
      my $icmp = NetPacket::ICMP->decode($l4);
      my $payload = $icmp->{'data'};
   
      &parsePayload("$payload","$userdata");
   }
   else
   {
      print "Unknown packet!\n";
   }
}

my $err;
my $pcap_t;

$pcap_t = Net::Pcap::open_offline($ARGV[0],\$err);

Net::Pcap::loop($pcap_t, 0, \&getPayload, 1);

Net::Pcap::close($pcap_t);

print "Done.\n";
[download]

Why do I want such a thing? I need to match regular expressions with payloads.

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